<template>
  <!-- #ifndef APP-NVUE -->
  <view :class="['uni-col', sizeClass, pointClassList]" :style="{
		paddingLeft:`${Number(gutter)}rpx`,
		paddingRight:`${Number(gutter)}rpx`,
	}">
    <slot></slot>
  </view>
  <!-- #endif -->
  <!-- #ifdef APP-NVUE -->
  <!-- 在nvue上，类名样式不生效，换为style -->
  <!-- 设置right正值失效，设置 left 负值 -->
  <view :class="['uni-col']" :style="{
		paddingLeft:`${Number(gutter)}rpx`,
		paddingRight:`${Number(gutter)}rpx`,
		width:`${nvueWidth}rpx`,
		position:'relative',
		marginLeft:`${marginLeft}rpx`,
		left:`${right === 0 ? left : -right}rpx`
	}">
    <slot></slot>
  </view>
  <!-- #endif -->
</template>

<script>
/**
 * Col  布局-列
 * @description  搭配uni-row使用，构建布局。
 * @tutorial  https://ext.dcloud.net.cn/plugin?id=3958
 *
 * @property  {span} type = Number 栅格占据的列数
 *            默认 24
 * @property  {offset} type = Number 栅格左侧的间隔格数
 * @property  {push} type = Number 栅格向右移动格数
 * @property  {pull} type = Number 栅格向左移动格数
 * @property  {xs} type = [Number, Object] <768px 响应式栅格数或者栅格属性对象
 *            @description  Number时表示在此屏幕宽度下，栅格占据的列数。Object时可配置多个描述{span: 4, offset: 4}
 * @property  {sm} type = [Number, Object] ≥768px 响应式栅格数或者栅格属性对象
 *            @description  Number时表示在此屏幕宽度下，栅格占据的列数。Object时可配置多个描述{span: 4, offset: 4}
 * @property  {md} type = [Number, Object] ≥992px 响应式栅格数或者栅格属性对象
 *            @description  Number时表示在此屏幕宽度下，栅格占据的列数。Object时可配置多个描述{span: 4, offset: 4}
 * @property  {lg} type = [Number, Object] ≥1200px 响应式栅格数或者栅格属性对象
 *            @description  Number时表示在此屏幕宽度下，栅格占据的列数。Object时可配置多个描述{span: 4, offset: 4}
 * @property  {xl} type = [Number, Object] ≥1920px 响应式栅格数或者栅格属性对象
 *            @description  Number时表示在此屏幕宽度下，栅格占据的列数。Object时可配置多个描述{span: 4, offset: 4}
 */
const ComponentClass = 'uni-col';

// -1 默认值，因为在微信小程序端只给Number会有默认值0
export default {
  name: 'uniCol',
  // #ifdef MP-WEIXIN
  options: {
    virtualHost: true // 在微信小程序中将组件节点渲染为虚拟节点，更加接近Vue组件的表现
  },
  // #endif
  props: {
    span: {
      type: Number,
      default: 24
    },
    offset: {
      type: Number,
      default: -1
    },
    pull: {
      type: Number,
      default: -1
    },
    push: {
      type: Number,
      default: -1
    },
    xs: [Number, Object],
    sm: [Number, Object],
    md: [Number, Object],
    lg: [Number, Object],
    xl: [Number, Object]
  },
  data() {
    return {
      gutter: 0,
      sizeClass: '',
      parentWidth: 0,
      nvueWidth: 0,
      marginLeft: 0,
      right: 0,
      left: 0
    }
  },
  created() {
    // 字节小程序中，在computed中读取$parent为undefined
    let parent = this.$parent;

    while (parent && parent.$options.componentName !== 'uniRow') {
      parent = parent.$parent;
    }

    this.updateGutter(parent.gutter)
    parent.$watch('gutter', (gutter) => {
      this.updateGutter(gutter)
    })

    // #ifdef APP-NVUE
    this.updateNvueWidth(parent.width)
    parent.$watch('width', (width) => {
      this.updateNvueWidth(width)
    })
    // #endif
  },
  computed: {
    sizeList() {
      let {
        span,
        offset,
        pull,
        push
      } = this;

      return {
        span,
        offset,
        pull,
        push
      }
    },
    // #ifndef APP-NVUE
    pointClassList() {
      let classList = [];

      ['xs', 'sm', 'md', 'lg', 'xl'].forEach(point => {
        const props = this[point];
        if (typeof props === 'number') {
          classList.push(`${ComponentClass}-${point}-${props}`)
        } else if (typeof props === 'object' && props) {
          Object.keys(props).forEach(pointProp => {
            classList.push(
                pointProp === 'span' ?
                    `${ComponentClass}-${point}-${props[pointProp]}` :
                    `${ComponentClass}-${point}-${pointProp}-${props[pointProp]}`
            )
          })
        }
      });

      // 支付宝小程序使用 :class=[ ['a','b'] ]，渲染错误
      return classList.join(' ');
    }
    // #endif
  },
  methods: {
    updateGutter(parentGutter) {
      parentGutter = Number(parentGutter);
      if (!isNaN(parentGutter)) {
        this.gutter = parentGutter / 2
      }
    },
    // #ifdef APP-NVUE
    updateNvueWidth(width) {
      // 用于在nvue端，span，offset，pull，push的计算
      this.parentWidth = width;
      ['span', 'offset', 'pull', 'push'].forEach(size => {
        const curSize = this[size];
        if ((curSize || curSize === 0) && curSize !== -1) {
          let RPX = 1 / 24 * curSize * width
          RPX = Number(RPX);
          switch (size) {
            case 'span':
              this.nvueWidth = RPX
              break;
            case 'offset':
              this.marginLeft = RPX
              break;
            case 'pull':
              this.right = RPX
              break;
            case 'push':
              this.left = RPX
              break;
          }
        }
      });
    }
    // #endif
  },
  watch: {
    sizeList: {
      immediate: true,
      handler(newVal) {
        // #ifndef APP-NVUE
        let classList = [];
        for (let size in newVal) {
          const curSize = newVal[size];
          if ((curSize || curSize === 0) && curSize !== -1) {
            classList.push(
                size === 'span' ?
                    `${ComponentClass}-${curSize}` :
                    `${ComponentClass}-${size}-${curSize}`
            )
          }
        }
        // 支付宝小程序使用 :class=[ ['a','b'] ]，渲染错误
        this.sizeClass = classList.join(' ');
        // #endif
        // #ifdef APP-NVUE
        this.updateNvueWidth(this.parentWidth);
        // #endif
      }
    }
  }
}
</script>

<style lang='scss' scoped>
/* breakpoints */
$--sm: 768px !default;
$--md: 992px !default;
$--lg: 1200px !default;
$--xl: 1920px !default;

$breakpoints: ('xs' : (max-width: $--sm - 1),
    'sm' : (min-width: $--sm),
    'md' : (min-width: $--md),
    'lg' : (min-width: $--lg),
    'xl' : (min-width: $--xl));

$layout-namespace: ".uni-";
$col: $layout-namespace+"col";

@function getSize($size) {
  @return 1 / 24 * $size * 100 * 1%;
}

@mixin res($key, $map:$breakpoints) {
  @if map-has-key($map, $key) {
    @media screen and #{inspect(map-get($map,$key))} {
      @content;
    }
  } @else {
    @warn "Undeinfed point: `#{$key}`";
  }
}

/* #ifndef APP-NVUE */
#{$col} {
  float: left;
  box-sizing: border-box;
}

#{$col}-0 {
  /* #ifdef APP-NVUE */
  width: 0;
  height: 0;
  margin-top: 0;
  margin-right: 0;
  margin-bottom: 0;
  margin-left: 0;
  /* #endif */
  /* #ifndef APP-NVUE */
  display: none;
  /* #endif */
}

@for $i from 0 through 24 {
  #{$col}-#{$i} {
    width: getSize($i);
  }

  #{$col}-offset-#{$i} {
    margin-left: getSize($i);
  }

  #{$col}-pull-#{$i} {
    position: relative;
    right: getSize($i);
  }

  #{$col}-push-#{$i} {
    position: relative;
    left: getSize($i);
  }
}

@each $point in map-keys($breakpoints) {
  @include res($point) {
    #{$col}-#{$point}-0 {
      display: none;
    }

    @for $i from 0 through 24 {
      #{$col}-#{$point}-#{$i} {
        width: getSize($i);
      }

      #{$col}-#{$point}-offset-#{$i} {
        margin-left: getSize($i);
      }

      #{$col}-#{$point}-pull-#{$i} {
        position: relative;
        right: getSize($i);
      }

      #{$col}-#{$point}-push-#{$i} {
        position: relative;
        left: getSize($i);
      }
    }
  }
}

/* #endif */
</style>
